Materials Green roofing

Create an energy-efficient home or office by planting a rooftop garden on your building’s uppermost surface. You’ll not only reduce cooling and heating costs, but you’ll be providing valuable wildlife habitat. A bonus: you may qualify for LEED certification points.

Benefits
Though green roofs are often pricier up-front than conventional roofs, they provide financial benefits to building owners in two ways. First, because they can reduce heat gain by up to 95 percent, they help reduce cooling costs.[2] Through the process of evapotranspiration, vegetated roofs reduce overheating of buildings so that the temperature indoors remains relatively cool during very hot months.[3] Studies conducted by the Centre for the Advancement of Green Roof Technology demonstrated that the outer membrane of a green-roofed building experienced 68 days of 20°C and zero days of 30°C temperatures, compared to a conventional building which had 257 days of 20°C and 206 days of 30°C temperatures.[4] In winter months intensive green roofs with thicker layers of soil and more substantial vegetation keep heat within a building by protecting it from wind which draws heat away

A second financial benefit of a green roof comes from their ability to protect roofing materials beneath. Green roofs cover and protect roof membranes, shielding them from heat and ultra-violet radiation, thermal stress (expansion and contraction), and physical stress (wind, hail, foot traffic).[2] This results in roof lifespans that are two to three times longer than conventional roofs, thus requiring fewer roof replacements.[6] The typical green roof lifespan is estimated around 40 years.[7]

Rooftop gardens have been shown to filter airborne particulates and remove carbon dioxide from the atmosphere.[10] They also filter and retain stormwater. The substrate used for green roofs filters any rainwater that happens to runoff, but retains a good portion of rainwater until it is taken up by the vegetation planted there, resulting in runoff decreases up to 28 percent. This reduces the strain on municipal water systems and may help to prevent freshwater contamination by overflowing sewage in wastewater facilities.[11]

Seattle Green roofs also provide recreational space that can be used as healthy retreat spaces for employees, educational environments for daycares, and therapeutic areas for patients in hospitals.[10] Additionally, green spaces can provide habitat to wildlife and insects, including some rare and endangered species here in Seattle.[12]

Types of green roofs
Ecoroofs fall into two general categories:

Extensive

  • Vegetation: generally accommodates groundcover species, succulents, and grasses
  • Substrate depth: one to 6 inches
  • Weight: building structure must be able to handle a load 12-50 pounds per square foot heavier than conventional roof structures
  • Access & maintenance: requires little maintenance (annual inspections) and therefore infrequent access
  • Drainage & irrigation: uses simple irrigation and drainage systems
Intensive
  • Vegetation: larger species, including trees, shrubs, high-maintenance gardens
  • Substrate depth: one foot or greater
  • Weight: building structure must be able to handle a load 80-150 pounds per square foot heavier than conventional roof structures
  • Access & maintenance: frequent access required for higher levels of maintenance and should include railings, lighting, etc.
  • Drainage & irrigation: requires more complex irrigation and drainage systems

Element Smart Roofing has partnered with Dura-Last to provide the perfect waterproofing membrane for your Seattle Green Roof or Roof Garden. The PVC used does not require any root barriers thus allowing a vast array of vegetative systems to be applied. Element Smart Roofing has partnered with expert landscaping companies who excel in installing both intensive and extensive Seattle green roof systems.

Here is some information regarding incentives for installing a green roof in Seattle.